Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C41/00—Preparation of ethers; Preparation of compounds having groups, groups or groups
  • C07C41/01—Preparation of ethers
  • C07C41/18—Preparation of ethers by reactions not forming ether-oxygen bonds
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C41/00—Preparation of ethers; Preparation of compounds having groups, groups or groups
  • C07C41/01—Preparation of ethers
  • C07C41/18—Preparation of ethers by reactions not forming ether-oxygen bonds
  • C07C41/22—Preparation of ethers by reactions not forming ether-oxygen bonds by introduction of halogens; by substitution of halogen atoms by other halogen atoms
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
  • C07C51/09—Preparation of carboxylic acids or their salts, halides or anhydrides from carboxylic acid esters or lactones
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
  • C07C51/347—Preparation of carboxylic acids or their salts, halides or anhydrides by reactions not involving formation of carboxyl groups
  • C07C51/367—Preparation of carboxylic acids or their salts, halides or anhydrides by reactions not involving formation of carboxyl groups by introduction of functional groups containing oxygen only in singly bound form
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C67/00—Preparation of carboxylic acid esters
  • C07C67/30—Preparation of carboxylic acid esters by modifying the acid moiety of the ester, such modification not being an introduction of an ester group
  • C07C67/31—Preparation of carboxylic acid esters by modifying the acid moiety of the ester, such modification not being an introduction of an ester group by introduction of functional groups containing oxygen only in singly bound form

Definitions

• the present invention relates to a novel carboxylic acid or a salt thereof, which is useful as an intermediate of 1,1,1,3,3,3-hexafluoro-2-methoxypropane, a process for producing the same, and a process for producing 1,1,1,3,3,3-hexafluoro-2-methoxypropane.
• 1,1,1,3,3,3-Hexafluoro-2-methoxypropane represented by the chemical formula: (CF 3 ) 2 CH(OCH 3 ), is a material useful as a raw material for the anesthetic Sevoflurane (see Patent Documents 1, 2, etc. listed below).
• the production of Sevoflurane at low cost is an important issue, and various processes have so far been contemplated.
• Patent Document 1 discloses a process wherein 1,1,1,3,3,3-hexafluoro-2-propyl methyl ether, obtained by methylation of hexafluoroisopropanol (HFIP), is reacted with chlorine gas to give 1,1,1,3,3,3-hexafluoro-2-propyl chloromethyl ether, and then this compound is reacted with KF in an organic solvent to produce Sevoflurane; a process wherein 1,1,1,3,3,3-hexafluoro-2-propyl methyl ether is reacted with BrF 3 ; and a process wherein HFIP is reacted with hydrogen fluoride and formaldehyde.
• HFIP hexafluoroisopropanol
• Patent Document 3 listed below discloses a process wherein hydrogen fluoride and paraformaldehyde are reacted with HFIP in the presence of sulfuric acid.
• Patent Document 2 listed below discloses a process wherein the methyl ether of HFIP is reacted with chlorine gas to produce 1,1,1,3,3,3-hexafluoro-2-propyl chloromethyl ether, which is then reacted with hydrogen fluoride and amine.
• Patent Document 4 listed below discloses a process wherein a polyether compound formed as a by-product during the reaction is reacted with hydrogen fluoride and a reaction accelerator such as sulfuric acid or the like to produce Sevoflurane.
• Patent Document 5 listed below discloses a process wherein hydrogen fluoride and paraformaldehyde are reacted with HFIP in the presence of sulfuric acid, and the formed Sevoflurane is extracted from the mixture at equilibrium by distillation or extraction, thereby increasing the yield.
• Patent Document 6 discloses a process wherein HFIP is reacted with bis(fluoromethyl)ether in the presence of acid.
• a number of processes for producing Sevoflurane are known, and most of these processes use HFIP as a starting material.
• a process for producing HFIP a process wherein hexafluoroacetone or its hydrate is reduced by hydrogen in the presence of a catalyst (see Patent Documents 7, 8 listed below, etc.) is known.
• Patent Document 9 a process wherein hexafluoropropylene oxide is rearranged in the presence of a catalyst
• Patent Document 10 a process wherein hexachloroacetone is fluorinated with hydrogen fluoride
• the former process has a problem in that the starting material, i.e., hexafluoropropylene oxide, is expensive.
• the latter process also has problems in that the purification processes for separating the resulting hexafluoroacetone from hydrochloric acid, for separating the byproduct chlorofluoroacetone, and the like are complicated, making the process costly.
• Patent Document 11 discloses a process for producing hexafluoroacetone hydrate, wherein HIME is reacted with oxygen under photoradiation.
• Patent Document 12 discloses a process for producing hexafluoroacetone or its hydrate, wherein OIME or HIME is reacted with oxygen in the presence of an activated carbon catalyst.
• Patent Document 13 discloses a process for producing hexafluoroacetone, wherein OIME is reacted with triethylamine to give hexafluoroacetone oxime, which is then hydrolyzed with acid.
• Patent Document 14 discloses a process for producing hexafluoroacetone hydrate, wherein (CF 3 ) 2 C(OH)CO 2 CH 3 (methyl 3,3,3-trifluoro-2-trifluoromethyl-2-hydroxypropionate; hereinafter abbreviated to “MTTHP”) is hydrolyzed and then decarboxylated by reacting the hydrolysis product with a halogenating agent.
• MTHP methyl 3,3,3-trifluoro-2-trifluoromethyl-2-hydroxypropionate
• the process utilizing the photo-oxidation of HIME has problems in that it is difficult to industrially perform photoradiation, and that the yield is low.
• the oxidation process using an activated carbon catalyst has problems such as inability to perform a long-term operation due to significant degradation of the catalyst, a low selectivity of hexafluoroacetone, and the like.
• the process wherein OIME is reacted with triethylamine to give an oxime has a problem in that triethylamine, which is an auxiliary starting material, is expensive.
• MTTHP is hydrolyzed and then decarboxylated by halogenation uses an inexpensive auxiliary starting material and has a high yield, but it has the drawback of requiring a large number of steps.
• Patent Document 15 discloses a process for producing HFIP, comprising synthesizing MTTHP by oxidation of HIME, hydrolyzing the resulting MTTHP, and decarboxylating the hydrolysis product in the presence of a protonic solvent.
• this process was found to have a low yield because of the formation of CF 3 (HCF 2 )C ⁇ O (pentafluoroacetone) as a by-product during decarboxylation.
• a primary object of the invention is to provide a process capable of efficient and low-cost production of 1,1,1,3,3,3-hexafluoro-2-methoxypropane, represented by the general formula: (CF 3 ) 2 CH(OCH 3 ), which is useful as a raw material for the anesthetic Sevoflurane, and a novel compound useful in the production of 1,1,1,3,3,3-hexafluoro-2-methoxypropane.
• a novel carboxylic acid or a salt thereof can be produced in a high yield according to a process using a known compound, 3,3,3-trifluoro-2-trifluoromethyl-2-hydroxypropionic ester, as a starting material, wherein the hydroxy group thereof is reacted with a methylating agent and then the resulting product is hydrolyzed, or according to a process wherein the above-mentioned starting material is hydrolyzed and then reacted with a methylating agent.
• the inventors also found that, by decarboxylating the novel carboxylic acid or the salt thereof by heat treatment, the target 1,1,1,3,3,3-hexafluoro-2-methoxypropane can be produced in a good yield, using a relatively simple process. Furthermore, the inventors found that the target 1,1,1,3,3,3-hexafluoro-2-methoxypropane can also be obtained by reacting a specific fluorinating agent with an olefin formed during the decarboxylation reaction as a by-product. The present invention was accomplished based on these findings.
• the invention provides a novel carboxylic acid compound and a production process therefor, as well as a process for producing 1,1,1,3,3,3-hexafluoro-2-methoxypropane from the carboxylic acid compound, as summarized below.
• Item 1 2-Methoxy-2-trifluoromethyl-3,3,3-trifluoropropionic acid represented by chemical formula (1): (CF 3 ) 2 C(OCH 3 )COOH or a salt thereof.
• Item 2 A process for producing 1,1,1,3,3,3-hexafluoro-2-methoxypropane represented by chemical formula (2): (CF 3 ) 2 CH(OCH 3 ), comprising decarboxylating 2-methoxy-2-trifluoromethyl-3,3,3-trifluoropropionic acid represented by chemical formula (1): (CF 3 ) 2 C(OCH 3 )COOH or a salt thereof.
• Item 3 The process for producing 1,1,1,3,3,3-hexafluoro-2-methoxypropane according to Item 2, wherein the decarboxylation reaction is performed in the presence of an organic solvent.
• Item 8 A process for producing 1,1,1,3,3,3-hexafluoro-2-methoxypropane represented by chemical formula (2): (CF 3 ) 2 CH(OCH 3 ), comprising reacting 1,1,1,3,3,3-hexafluoro-2-methoxy-2-propene represented by chemical formula (4): CF 2 ⁇ C(CF 3 )(OCH 3 ) with one or more fluorinating agents represented
• R is a hydrocarbon group, and may contain at least one atom selected from the group consisting of halogen, oxygen, nitrogen, and sulfur atoms, and subsequently hydrolyzing the resulting reaction product.
• methylating agent is at least one compound selected from the group consisting of dimethyl sulfate, chloromethane, bromomethane, and iodomethane.
• Item 10 A process for producing 2-methoxy-2-trifluoromethyl-3,3,3-trifluoropropionic acid represented by chemical formula (1): (CF 3 ) 2 C(OCH 3 )COOH or a salt thereof, comprising hydrolyzing a hydroxycarboxylic ester represented by general formula (3): (CF 3 ) 2 C(OH)COOR, wherein R is a hydrocarbon group, and may contain at least one atom selected from the group consisting of halogen, oxygen, nitrogen, and sulfur atoms, to produce 1,1,1-trifluoro-2-trifluoromethyl-2-hydroxypropionic acid represented by the chemical formula: (CF 3 ) 2 C(OH)CO 2 H or a salt thereof, and subsequently reacting the resulting product with a methylating agent.
• novel carboxylic acid compound useful as an intermediate of 1,1,1,3,3,3-hexafluoro-2-methoxypropane and the production process therefor are described first below, and subsequently the process for producing 1,1,1,3,3,3-hexafluoro-2-methoxypropane from the carboxylic acid compound is described.
• novel carboxylic acid or salt thereof useful as an intermediate of 1,1,1,3,3,3-hexafluoro-2-methoxypropane, can be produced using, as a starting material, a hydroxycarboxylic ester represented by general formula (3): (CF 3 ) 2 C(OH)COOR, wherein R is a hydrocarbon group, and may contain at least one atom selected from the group consisting of halogen, oxygen, nitrogen, and sulfur atoms.
• R is a hydrocarbon group, and may contain at least one atom selected from the group consisting of halogen, oxygen, nitrogen, and sulfur atoms.
• the compound of general formula (3) is known and described in, for example, Japanese Unexamined Patent Publication No. 2002-234860.
• examples of hydrocarbon groups represented by R include C 1 -C 10 alkyl, aryl, aralkyl, and the like.
• the alkyl are methyl, ethyl, isopropyl, t-butyl, and hexyl.
• the aryl are phenyl, naphthyl, pyridyl, chlorophenyl, and the like.
• the aralkyl are benzyl, phenethyl, and the like.
• methyl is particularly preferable because of production at low cost.
• 2-Methoxy-2-trifluoromethyl-3,3,3-trifluoropropionic acid represented by chemical formula (1) above or a salt thereof is a novel compound not disclosed by any literature, and is useful as an intermediate of 1,1,1,3,3,3-hexafluoro-2-methoxypropane.
• Examples of the salts of the carboxylic acid represented by chemical formula (1) above include various metal salts, ammonium salts, and the like. More specifically, salts of monovalent cations such as Li + , Na + , K + , NH 4 + , H + , Ag + , and the like; salts of divalent cations such as 1/2Mg 2+ , 1/2Ca 2+ , 1/2Ba 2+ , 1/2Pb 2+ , 1/2Cu 2+ , and the like; salts of trivalent cations such as 1/3Al 3+ , 1/3Fe 3+ , and the like can be mentioned. Among these salts, salts of Li + , Na + , K + , 1/2Mg 2+ , 1/2Ca 2+ , and the like are particularly preferable because they can be easily obtained by hydrolyzing esters.
• the hydroxycarboxylic ester represented by general formula (3) can be methylated by reacting the hydroxycarboxylic ester with a methylating agent in the presence of an alkaline compound. This reaction can be performed either in the presence or absence of a solvent.
• methylating agents Compounds known as general methylating agents for alcohols are usable as the methylating agent.
• Specific examples of methylating agents include halogenated methanes such as chloromethane (CH 3 Cl), bromomethane (CH 3 Br), iodomethane (CH 3 I), and the like, as well as dimethyl sulfate, dimethyl carbonate, and the like.
• the amount of methylating agent may be from about 0.2 to about 10 equivalents, preferably about 1 to about 2 equivalents, and more preferably about 1 to 1.5 equivalents, per equivalent of the hydroxycarboxylic ester represented by general formula (3).
• alkaline compound During the methylation, it is necessary to add an alkaline compound to convert the hydroxy group into an alkoxide.
• alkaline compound include carbonates, hydrogen carbonates, hydroxides, oxides, and the like of alkali metals (such as Li, K, Na, and the like) or alkaline earth metals (such as Mg, Ca, Ba, and the like).
• the amount of alkaline compound may be from about 0.2 to about 10 equivalents, preferably about 1 to about 2 equivalents, and more preferably about 1 to about 1.5 equivalents, per equivalent of the hydroxycarboxylic ester represented by general formula (3).
• reaction temperature depends on the type of methylating agent, it may typically be from about 0 to about 200° C., preferably about 20 to about 120° C., and more preferably about 30 to about 100° C.
• the reaction time may typically be from about 10 minutes to about 24 hours, and preferably about 1 to about 10 hours.
• the methylated ester compound thus obtained in the step described above can be hydrolyzed by reacting it with water in the presence of an alkaline compound or an acid catalyst to produce 2-methoxy-2-trifluoromethyl-3,3,3-trifluoropropionic acid represented by chemical formula (1) or its salt.
• alkaline compounds that can be suitably used include hydroxides, oxides, carbonates, and the like of alkali metals (such as Li, K, Na, and the like) or alkaline earth metals (such as Mg, Ca, Ba, and the like).
• acid catalysts that can be suitably used include sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, and the like.
• the amount of alkaline compound may be from about 0.2 to about 10 equivalents, preferably about 1 to about 2 equivalents, and more preferably about 1 to about 1.5 equivalents, per equivalent of the methylated ester compound.
• the amount of acid catalyst may be from about 0.01 to about 10 equivalents, and preferably about 0.1 to about 1 equivalent, per equivalent of the methylated ester compound.
• reaction temperature cannot be generalized because it depends on the type of the alkaline compound or acid catalyst, it may typically be from about 0 to about 100° C., preferably about 20 to about 80° C., and more preferably about 30 to about 60° C.
• the reaction time may typically be from about 10 minutes to about 24 hours, and preferably about 1 to about 10 hours.
• 2-Methoxy-2-trifluoromethyl-3,3,3-trifluoropropionic acid represented by chemical formula (1) above can be produced by hydrolysis in the presence of an acid catalyst.
• salts of the carboxylic acid salts of Li, K, Na, Mg, Ca, and the like can be produced by hydrolysis in the presence of an alkaline compound containing any of these metal components.
• Salts of other metal atoms, ammonium salts, and the like can be produced from the acid represented by general formula (1) or its salt via a salt-exchange reaction or a salt-forming reaction.
• the carboxylic acid represented by general formula (1): (CF 3 ) 2 C(OCH 3 )COOH or its salt can also be produced by hydrolyzing the hydroxycarboxylic ester represented by general formula (3) above to produce 1,1,1-trifluoro-2-trifluoromethyl-2-hydroxypropionic acid represented by the chemical formula: (CF 3 ) 2 C(OH)CO 2 H or its salt, and subsequently reacting the resulting product with a methylating agent.
• Hydrolysis of the hydroxycarboxylic ester represented by general formula (3) can be performed in the same manner as the hydrolysis of the methylated ester compound in the above-described first process.
• Salts of Li, K, Na, Mg, Ca, and the like can be produced by hydrolysis in the presence of an alkaline compound containing any of these metal components.
• Salts of other metal atoms, ammonium salts, and the like can be produced by a salt-exchange reaction or a salt-forming reaction from 1,1,1-trifluoro-2-trifluoromethyl-2-hydroxypropionic acid represented by the chemical formula: (CF 3 ) 2 C(OH)CO 2 H or its salt obtained by hydrolysis.
• 1,1,1-Trifluoro-2-trifluoromethyl-2-hydroxypropionic acid or its salt is subsequently reacted with a methylating agent to produce the carboxylic acid represented by general formula (1): (CF 3 ) 2 C(OCH 3 )COOH or a salt thereof.
• reaction with a methylating agent can be performed under the same conditions as employed in the reaction of the hydroxycarboxylic ester with a methylating agent in the above-described first process.
• 1,1,1,3,3,3-hexafluoro-2-methoxypropane represented by chemical formula (2): (CF 3 ) 2 CH(OCH 3 ) can be produced via the decarboxylation reaction by heating 2-methoxy-2-trifluoromethyl-3,3,3-trifluoropropionic acid represented by chemical formula (1): (CF 3 ) 2 C(OCH 3 )COOH or its salt obtained according to the above-described first or second process.
• the decarboxylation reaction can be performed by heating the carboxylic acid represented by chemical formula (1) or its salt.
• the carboxylic acid represented by chemical formula (1) When the carboxylic acid represented by chemical formula (1) is used, it may be heated in a solid state; however, when a salt of the carboxylic acid represented by chemical formula (1) is used, it is necessary to perform the decarboxylation reaction in the presence of water. In this case, it is necessary to use an equimolar or excess amount of water relative to the salt of the carboxylic acid represented by chemical formula (1).
• the carboxylic acid or its salt may be heated in aqueous solution form, using water as a solvent.
• the concentration of the carboxylic acid represented by chemical formula (1) or its salt is not limited; however, the concentration may typically be from about 0.1 to about 60 mass %, and the aqueous solution may contain the carboxylic acid or its salt in an amount that exceeds the saturated concentration. Especially at a high concentration, the reaction can be efficiently performed.
• the yield of the target material, 1,1,1,3,3,3-hexafluoro-2-methoxypropane represented by general formula (2): (CF 3 ) 2 CH(OCH 3 ), can be enhanced by performing the above-described decarboxylation reaction in the presence of an organic solvent to thereby reduce the production of an olefin compound represented by chemical formula (4): CF 2 ⁇ C(CF 3 )(OCH 3 ), which is a by-product formed during the decarboxylation reaction, a hydrolysis product represented by chemical formula (5): CF 3 CH(OCH 3 )(COONa), and the like.
• Solvents with a high dielectric constant are preferably used as organic solvents, and examples of such organic solvents that can be suitably used include amide solvents such as N,N-dimethylformamide, N-methylpyrrolidone, N,N-dimethylacetamide, and the like; nitrile solvents such as acetonitrile, propionitrile, and the like; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and the like; sulfoxide solvents such as dimethyl sulfoxide and the like; and sulfone solvents such as sulfolane and the like. These organic solvents can be used alone or in combination.
• concentration of the carboxylic acid represented by chemical formula (1): (CF 3 ) 2 C(OCH 3 )COOH or its salt in an organic solvent is not limited, it may typically be from about 0.01 to about 1 mol/L.
• the decarboxylation reaction When the decarboxylation reaction is performed in an organic solvent, water may be added, and the reaction may be performed in a mixed solvent.
• a mixed solvent the ratio of water to organic solvent is not limited, but may, for example, be from about 100:1 to about 1:100 by volume.
• the decarboxylation reaction may be performed after isolating the carboxylic acid represented by chemical formula (1) or its salt, or the decarboxylation reaction may be performed directly without isolating the carboxylic acid represented by chemical formula (1) or its salt.
• the carboxylic acid represented by chemical formula (1) or its salt is not isolated, one-pot decarboxylation can be performed from the starting hydroxycarboxylic ester of general formula (3).
• the reaction temperature during the decarboxylation reaction may typically be from about 60 to about 200° C., preferably from about 80 to about 150° C., and more preferably from about 80 to about 120° C.
• a reaction temperature that is too low is not preferable because the rate of reaction will become slow, whereas a reaction temperature that is too high is also not preferable because the amount of unwanted by-products will increase.
• additives include ethylene glycol, diethylene glycol, triethylene glycol, tetraethyleneglycol, monoalkyl ethers thereof such as monomethyl ethers, monoethyl ethers and the like, and dialkyl ethers thereof such as dimethyl ethers, diethyl ethers, and the like.
• the amount of the (polyethylene glycols and alkyl ethers thereof is from about 0 to about 100 parts by weight, and preferably from about 0.001 to about 10 parts by weight, per part by weight of the carboxylic acid represented by chemical formula (1) or its salt. If these additives are not used, the reaction time will be long, but the reaction will proceed without any problems.
• the reaction time depends upon the reaction temperature and the amount of additives. When the additives are used, a sufficient reaction time is from about 2 to about 5 hours at 80° C.
• one or more fluorinating agents represented by the chemical formula: MF.(HF) n , wherein M is H, Na, K, or Cs, and n is an integer from 0 to 2, can be added to further enhance the yield of the target 1,1,1,3,3,3-hexafluoro-2-methoxypropane represented by chemical formula (2).
• fluorinating agents represented by the chemical formula: MF.(HF) n include hydrogen fluoride, sodium fluoride, potassium fluoride, cesium fluoride, acidic potassium fluoride (KHF 2 ), acidic sodium fluoride (NaHF 2 ), and the like. These fluorinating agents can be used alone or in combination.
• the amount of the fluorinating agent represented by the chemical formula: MF.(HF) n is preferably from about 0.01 to about 3 equivalents, and more preferably about 0.5 to about 1.2 equivalents, per equivalent of the carboxylic acid represented by chemical formula (1) or its salts.
• the fluorinating agent can be used in both methods wherein the decarboxylation reaction is performed in a solid state, and wherein the decarboxylation reaction is performed in a solution.
• the fluorinating agent is sodium fluoride, potassium fluoride, or cesium fluoride
• the reaction must be performed in the presence of about an equimolar or excess amount of water relative to the fluorinating agent.
• Patent Document 15 Japanese Unexamined Patent Publication No. 2002-234860 discloses a process for producing HFIP by decarboxylating the compound represented by general formula (3); with this process, however, even if decarboxylation is performed under acidic conditions, a large amount of the by-product, pentafluoroacetone represented by HCF 2 COCF 3 , is formed to decrease the yield.
• the pH of the reaction solution does not affect the yield of the target material, and, regardless of whether an acid is added or not, such a by-product in which the CF 3 group has been replaced with a CF 2 H group is not formed, thus resulting in decarboxylation at a high yield.
• 1,1,1,3,3,3-Hexafluoro-2-methoxypropane represented by chemical formula (2) can also be produced according to a process wherein 1,1,1,3,3,3-hexafluoro-2-methoxy-2-propene represented by chemical formula (4): CF 2 ⁇ C(CF 3 )(OCH 3 ) (hereinafter referred to as an “olefin compound”) is reacted with the above-described one or more fluorinating agents represented by the chemical formula: MF.(HF) n , wherein M is H, Na, K, or Cs, and n is an integer from 0 to 2.
• the reaction between the olefin compound represented by chemical formula (4): CF 2 ⁇ C(CF 3 )(OCH 3 ) and the fluorinating agent represented by the chemical formula: MF.(HF) n can be performed using, for example, the above-mentioned organic solvent, water, or a mixed solvent of the above-mentioned organic solvent and water.
• the concentration of the olefin compound represented by chemical formula (4): CF 2 ⁇ C(CF 3 )(OCH 3 ) in a solution may typically be from about 0.1 to about 8 mol/L.
• amide solvents such as N,N-dimethylformamide, N-methylpyrrolidone, N,N-dimethylacetamide, and the like; nitrile solvents such as acetonitrile, propionitrile, and the like; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and the like; sulfoxide solvents such as dimethyl sulfoxide and the like; or sulfone solvents such as sulfolane and the like are used as the organic solvent, the target 1,1,1,3,3,3-hexafluoroisopropyl ether compound represented by general formula (2) can be produced at high yield.
• amide solvents such as N,N-dimethylformamide, N-methylpyrrolidone, N,N-dimethylacetamide, and the like
• nitrile solvents such as acetonitrile, propionitrile, and the like
• ketone solvents
• the reaction must be performed in the presence of about an equimolar or excess amount of water relative to the fluorinating agent.
• the amount of the fluorinating agent represented by the chemical formula: MF.(HF) n is preferably from about 1 to about 2 equivalents per equivalent of the olefin compound represented by chemical formula (4): CF 2 ⁇ C(CF 3 )(OCH 3 ).
• the reaction between the olefin compound represented by chemical formula (4): CF 2 ⁇ C(CF 3 )(OCH 3 ) and the fluorinating agent represented by the chemical formula: MF.(HF) n can be typically performed within the range of temperatures from about 60 to about 120° C. While the reaction atmosphere at that time is not limited, the reaction is preferably performed in a sealed system with an inert gas atmosphere such as N 2 or the like.
• reaction time depends upon the reaction temperature, the amount of additives, and the like, it is typically from about 1 to about 10 hours.
• the 1,1,1,3,3,3-hexafluoro-2-methoxypropane of chemical formula (2) obtained by the above-described decarboxylation reaction or HF addition reaction can be separated and purified according to a known process.
• purification can be performed according to processes such as distillation, extraction, etc.
• 1,1,1,3,3,3-hexafluoro-2-methoxypropane which is useful as an anesthetic compound or a raw material thereof, can be produced efficiently and at low cost, using a known hydroxycarboxylic ester represented by general formula (3) as a starting material.
• novel carboxylic acid represented by chemical formula (1) or a salt thereof, which is useful as an intermediate or the like of 1,1,1,3,3,3-hexafluoro-2-methoxypropane can be produced in a high yield.
• the target (CF 3 ) 2 CH(OCH 3 ) is denoted as “HFMOP”; the by-product CF 2 ⁇ C(CF 3 )(OCH 3 ) was denoted as an “olefin”; and CF 3 CH(OCH 3 )(COONa) was denoted as a “hydrolysis product”.
• the solvents are each denoted by the following abbreviations: NMP (N-methylpyrrolidone), MeCN (acetonitrile), DMSO (dimethylsulfoxide), and DMAc (N,N-dimethylacetamide).
• a 1 L SUS autoclave was charged with 150.5 g of 48.2 mass % aqueous (CF 3 ) 2 C(OCH 3 )CO 2 Na solution (active compound amount: 292.5 mmol) and 300 ml of NMP solvent. The autoclave was subsequently sealed, and the decarboxylation reaction was performed at about 130° C. for 5.5 hours.
• the autoclave was heated stepwise to about 110° C. to extract the contents (until the water flowed out).
• a 300 mL SUS autoclave was charged with 25.0 g (100.8 mmol) of (CF 3 ) 2 C(OCH 3 )CO 2 Na, 11.4 g (146.2 mmol) of KF.HF, and 25 g of water to prepare about a 50 mass % aqueous solution.
• the pressure inside the autoclave was then reduced, and the autoclave was charged with 100 ml of NMP by suction.
• the decarboxylation reaction was subsequently performed at about 130 to about 150° C. for about 6 hours.
• An ice bath trap and a dry-ice/acetone trap were connected to the reactor with a PFA tube. The pressure inside the autoclave was then released to the atmospheric pressure while stirring the contents.
• the autoclave was heated stepwise to about 110° C. to extract the contents (until the water flowed out).
• each product is denoted by the same abbreviation as used in Table 1.
• the following abbreviations are used: NMP (N-methylpyrrolidone), MeCN (acetonitrile), DMSO (dimethyl sulfoxide), DMAc (N,N-dimethylacetamide), and DMF (dimethylformamide).

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